A giant magnetoresistance (GMR) element formed by a multi-layer film including a ferromagnetic layer and a non-magnetic layer, and a tunneling magnetoresistance (TMR) element using an insulating layer (a tunnel barrier layer, a barrier layer) as a non-magnetic layer are known. In general, the TMR element has a higher element resistance than the GMR element, but the TMR element has a higher magnetoresistance (MR) ratio than the GMR element. For that reason, the TMR element has gained attention as an element for magnetic sensors, high-frequency components, magnetic heads, and non-volatile random access memories (MRAM).
As a writing method of an MRAM, a method of performing writing (magnetization reversal) by using a magnetic field caused by a current or a method of performing writing (magnetization reversal) by using a spin transfer torque (STT) generated by a current flowing in a lamination direction of the magnetoresistance element is known.
In the method of using a magnetic field, a problem arises in that the writing cannot be performed by a current flowing in a thin wiring when an element size decreases.
In contrast, in the method of using a spin transfer torque (STT), when one ferromagnetic layer (a fixed layer, a reference layer) spin-polarizes a current, the spin of the current is transferred to magnetization of another ferromagnetic layer (a free layer or a recording layer) and hence the writing (the magnetization reversal) is performed by the torque (STT) generated at that time. In this method, there is an advantage in that a current required for writing can be decreased as the element size decreases.